An organic light-emitting device, such as an organic electroluminescent device (organic EL device), has been actively studied for enhancing the light emission efficiency thereof. In particular, various studies for enhancing the light-emitting efficiency have been made by newly developing and combining an electron transporting material, a hole transporting material, a light-emitting material, a host material, and the like constituting an organic electroluminescent device. Among these, there are studies relating to an organic electroluminescent device utilizing a compound having a carborane structure.
Non-patent Document 1 describes the results of studies on the characteristics as a host material for blue phosphorescence of a carborane derivative represented by the following formula and a compound having a carbazolylphenyl group bonded to an o-position or a p-position of a carborane structure. However, the compounds described in Non-patent Document 1 are all symmetric molecules having the groups bonded to the carborane structure that are the same as each other, and a compound having different groups that are bonded to a carborane structure is not described.

Patent Document 1 describes a carborane derivative having silyl groups bonded thereto represented, for example, by the following formula and a compound having a silyl group and another group bonded to a carborane structure, and describes an example using the carborane derivative as a host material in a light-emitting layer present between a pair of electrodes constituting an organic electroluminescent device. However, the carborane derivatives shown in Patent Document 1 are all compounds having a silyl group bonded to a carborane structure, and the literature does not describe a carborane derivative having combined therewith a group other than a silyl group.

Patent Document 2 describes the usefulness of a carborane derivative represented by the following general formula as a material for an electron transporting layer of an organic electroluminescent device. In the formula herein, it is stated that R1 to R8 each represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted condensed polycyclic aromatic group, or a substituted or unsubstituted condensed polycyclic heterocyclic group, and compounds, in which R1 and R8 are carbazolylphenyl groups, are described as specific examples thereof. However, Patent Document 2 does not confirm the usefulness of the carborane derivative represented by the following general formula as a host material and a light-emitting material.
